VW PASSAT clutch issues

Hi, apologies if this is a repeat thread, for what I’ve read, this is a common problem with Passats.

RE: VW PASSAT 2.0 TDI 2012 Bluemotion

Last month my clutch went soft then it got stuck to the floor and didn’t return back to its position. The first thing I did was call RAC. They topped up the brake fluid because it was low, pumped the clutch a few times and it got back to normal function, but the next day, after about a 15-minute drive on the motorway, it went again.

I then took it to a garage, where they changed the master cylinder. Immediately after picking it up, the clutch kept getting sticky and as soon as I went on the motorway, it started going again.

I was then told by this garage that it was probably the slave cylinder that will need replacing, but considering the cost of replacing the slave cylinder, I decided to get it checked again at a different garage first. This other garage told me that most likely the new master cylinder is faulty or was damaged when fitted in, and they didn’t think it was the slave cylinder, because apparently the clutch box where the slave cylinder is, has a drain hole which they checked and apparently was dry.

I then went back to the first garage to discuss the issue again and was told that it was highly unlikely the new part is faulty, they still believed the slave cylinder is faulty but they said another common fault with these cars is the “pressure relief valve” so they said they would check/replace this before the change the slave cylinder (and clutch).

My question is, how likely is it that the fault is somewhere else and not the slave cylinder? The thing that’s making me question this is that after I pump the clutch a few times, then if I drive the car at a slower speed ie. on local roads, the clutch works absolutely fine, it’s only when I drive at a high speed on the motorway it’s when it gets sucked to the floor. Does this pressure relief valve have anything to do with this?

Any help is much appreciated!

I don’t think it does have anything to do with this unless there is debris inside that blocks flow. Change it and see. It is cheaper than the slave replacement… assuming the slave is a concentric type that require the trans be removed to replace it. Do the cheap stuff and hope that fixes it… then accept the cost iof a new slave (and a new clutch disk while you are spending that money)

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That’s consistent w/faulty CMC. Slave cylinders tend to be pretty robust, and if they fail they leak clutch fluid to the outside. If the clutch fluid level doesn’t go down enough to have to add more from time to time, slave problem unlikely. No idea what pressure relief valve does.

hmmm … when I first started reading your topic I was thinking the problem was the clutch pressure plate, requiring clutch replacement. That remains possible, but before that if I had this problem myself I’d replace the MC again, using a dealership oem part. That part is often located in a difficult to access corner of the engine compartment. Very easy for a shop tech to take a short cut. So make sure the shop tech who’s replacing the CMC has a good deal of experience doing that job. Worse case the current CMC is good, and you replaced it w/another good one. No problem, you can use the other good one later. CMC is a wear item and replacement is a pretty common thing. I’ve replaced that part on my Corolla 3 or 4 times over the years.

Thanks, George_San_Jose1. I was told a dealership part was used, I paid the higher-end price for it. The garage is good, but I wouldn’t be surprised if they got one of their apprentices to fit it in. I will definitely start with MC and then check everything else before changing the slave and clutch.

I think I’ve noticed one thing though, as I’ve said before it only happens when I’m driving on the motorway at a high speed, and when the clutch gets stuck down, the brake pedal seems to be going a bit soft as well, and when I pump the clutch the break gets harder - is the clutch connected to the break at all, do they share the hydraulic system? (sorry if it’s a dumb question).

It sounds like you might have a heat problem…with both brake and clutch.

The clutch and brake are seperate systems in the same location that might share only their resevoirs. Got that? If the clutch fluid boils, the pedal would get soft or drop completely. The same can be said of brakes. A hot engine close to each master and lines can overheat fluid and cause this. If there is a spot where the clutch and brake lines are close to the turbo that may be the issue. A heat sheild or wrap should help.

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That config has been used on some vehicles, but not a common thing in America/Asian cars. Not sure about your VW. Ask at the dealership , they should know. Other than the heat speculation above, it’s a puzzle at this point. Are you located in a location where it is currently hot weather, New Zealand or the like? If you’re in a cold North American climate, the heat theory seems unlikely unless engine configuration has been modified.

I live in England, UK. Sometimes the clutch goes as soon as I get on the motorway, so before the heats up fully.

Though - Sorry if this has nothing to do with the clutch issue, I’m just trying to give as much information as possible - the engine oil pressure gauge never stays on the midpoint on the meter, on hot days it gets close to it then drops down a little bit, and on cold days it doesn’t even get close to the mid-point.

Also - I told the first garage what the second one said about the drain hole on the clutch box, and I was told that the 2.0 models don’t have a drain hole - do you guys know if the 2.0 models have a drain hole in the gear box?

I’m guessing that drain hole isn’t in the gear box so much as in the clutch housing area. The clutch slave cyclinder is probably located inside the clutch housing, so he idea is , if the clutch slaves leaks clutch fluid, it will drip out that drain hole, giving the shop an indication the clutch slave cylinder has failed. But the drain hole isn’t really necessary, b/c if the slave cylinder fails the fluid in the clutch reservoir will go down, the level easily visible in the engine compartment , and the owner will have to add clutch fluid from time to time. So if the clutch fluid is going down for unexplained reasons, the shop is able to conclude the slave cylinder is leaking without having to inspect any drain holes in the clutch housing. BTW, clutch slave failure is an uncommon thing by reports here. Clutch master cylinder failure much more common. Clutch MC faliure is internal and doesn’t cause fluid level to go down.